Preparation and characteristics of composite sintered brick by iron ore tailing,coal gangue and sewage sludge

Composite sintered bricks，which main materials was consisted of iron tailings，coal gangue and sewage sludge，were preparation by using iron ore tailings and coal gangue as main raw materials and adding some sludge and other auxiliary materials in the paper.The minerals composition，chemical composition and particle sizes of iron ore tailings，gangue，sewage sludge and other auxiliary materials were analyzed.The effects of iron ore tailings，coal gangue and sewage sludge ratio，bricks’ body forming pressure and sintering temperature on the quality of sintered bricks were investigated，respectively.The curing effects and microstructure of heavy metal ions in sintered bricks were analyzed by means of XRD，SEM and ICP.The results show that the preparation conditions of iron ore tailings-coal gangue-sewage sludge composite sintered bricks are iron ore tailings：coal gangue：sludge：shale ratio is 54∶30∶6∶10，which forming pressure 20 MPa as well as sintering temperature 1 100 ℃，holding time 3.0 h is appropriate.After the high temperature sintering，the heavy metal in the materials is almost cured or partially volatilized.Meanwhile，the leaching rate of heavy metal ions is Pb²⁺> Cu²⁺> Zn²⁺> Cr³⁺ and conforms to GB5085.3—2007.Microscopic analysis shows that sections of the non sintered bricks are almost discrete particles，the size and arrangement of small particles are disordered.After the high temperature sintering，the newly formed glass with crystal phase is obviously increased and the liquid phase is consolidated，and the micro surface is more uniform and compact.